The present invention relates generally to a filter-detector housing assembly for a room air monitor and, more particularly, to a close-coupled filter-detector fixture capable of collecting and detecting the presence of alpha particles emitted from radioactive material in room environment air.
Accurate and timely monitoring of the air quality is necessary for protection of workers in radioactive environments, specifically in industrial environments processing plutonium. Monitoring room air quality for radiation exposure must take into account not only the radiation quantity but also the radiation quality. For a device to measure accurately the radioactive aerosol concentrations contributing to worker exposure to unknown or varying spectra of alpha particle energies, the device not only should collect and count the events but also should distinguish between the alpha particle radiation emitted from the airborne plutonium and the naturally occurring alpha particle radiation from radon.
There is an existing need for a room air monitor with a filter-detector system capable of simultaneous and continuous collection and counting of long-lived radionuclides, primarily transuranic elements, typically in the form of suspended particulates.
Also, there is an existing need for a system capable of collecting and counting particulates present in room environment air for monitoring containment control system effectiveness.
Further, there is an existing need for an open frame sample collection and counting system which eliminates sampling tubes or lines where sample loss can occur.
Several devices are commonly used to monitor the room air quality of industrial environments. Existing monitoring instruments detect penetrating radiation without collection of the radioactive material itself. Some instruments are designed for detecting radioactive gases where a continuous sample stream is constrained in a detector assembly as opposed to being collected. These monitoring techniques are primarily designed to detect intermediate to long-range ionizing radiation.
Other instruments have been designed to collect and count radioactive material emitting short to intermediate range ionizing radiation; however, the sample collection and counting processes are separated both spatially and temporally. These devices suffer, in various degrees, the disadvantage that collection and counting are not performed continuously and/or simultaneously.
Other devices which perform both collection and counting, such as specific plutonium aerosol monitors, suffer a major disadvantage in that particles can be lost to the housing fixture due to the spatial arrangement of the collector and the detector, and the resulting air flow pattern. Distance, impeding surfaces, sampling tubes or lines, etc., between the collection and detection functions of a room air monitor lead to inaccuracy in the sample collected and diminished sensitivity.
Thus, none of the existing instruments are specifically configured to detect very short-range ionizing radiation, primarily alpha particles, and to measure long-lived radionuclides, primarily transuranic aerosols.